The present invention relates to a heat exchanger preferably used as, for example, a heater core to be incorporated into a car air conditioner for a vehicle.
Herein and in the appended claims, the term “aluminum” encompasses aluminum alloys in addition to pure aluminum.
A heater core for a car air conditioner is a heat exchanger for heating the interior of a vehicle compartment by making use of warm cooling water for cooling an engine. In recent years, the temperature of the cooling water has decreased, because of improved performance of a radiator and a decrease in heat generation attributable to improved engine performance. Therefore, in order to satisfactorily heat the interior of the vehicle compartment, the performance of the heater core must be further enhanced.
A conventionally known heater core for use in a car air conditioner includes a pair of header tanks spaced apart from each other; a plurality of flat heat exchange tubes which are disposed between the two header tanks at predetermined intervals along a longitudinal direction of the header tanks with their width direction coinciding with an air flow direction and whose opposite end portions are connected to the corresponding header tanks; and a plurality of corrugate fins each including wave crest portions, wave trough portions, and flat connection portions connecting together the corresponding wave crest portions and wave trough portions, and each disposed between the adjacent heat exchange tubes. Each connection portion of each corrugate fin has a plurality of louvers which extend in the width direction of the connection portion and arranged in the longitudinal direction of the connection portion. In this heater core, the tube height of the heat exchange tube (thickness along the longitudinal direction of a header) is between 1.4 mm to 1.8 mm; the thickness of an elongated aluminum sheet used to form the heat exchange tube, or the tube wall thickness of the heat exchange tube, is 0.4 mm; the inner height of the heat exchange tube (tube height−tube wall thickness×2) is 0.6 mm to 1.0 mm; the width of the corrugate fin as measured in the air flow direction is between 21 mm to 32 mm; and the fin height of the corrugate fin, or the direct distance between the wave crest portion and the wave trough portion, is 2.5 mm to 5.0 mm (refer to Japanese Patent No. 3459271 (claim 1, paragraph 0012, and paragraph 0017)).
In the case of the heater core described in the publication, the performance of the heater core is improved by setting within respective ranges the tube height of the heat exchange tube, the tube wall thickness of the heat exchange tube, the inner height of the heat exchange tube, the width of the corrugate fin as measured in the air flow direction, and the fin height of the corrugate fin.
In order to optimize heat radiation and resistance to air flow, which are performance factors of a heater core, the inventors of the present invention focused on the louver pitch (the pitch of the louvers formed on each connection portion of each corrugate fin) and the inclination angle of the louvers in relation to the connection portion, and have thus achieved the present invention.